WASHINGTON, April 9 (Reuters) - New parents leaving U.S. hospitals often take home a corporate gift along with their babies: a tote bag filled with infant formula. Consumer advocates want to end the giveaways, which they say undermine breastfeeding.

In a letter to more than 2,600 hospitals, dozens of consumer and health organizations called on the facilities to stop distributing free samples of formula that they say entangles healthcare providers in pharmaceutical and food manufacturers' marketing and could be seen as an endorsement.

Giving formula to new parents discourages some new mothers from breastfeeding, the groups said on Monday in the letter sent by the advocacy group Public Citizen. They are also petitioning the $4 billion infant formula industry's leaders - Abbott Laboratories, Mead Johnson Nutrition Co and Nestle SA - to halt the practice.

Hospitals aim "to promote the health of infants and mothers, but the ongoing promotion of infant formula conflicts with this mission," Public Citizen President Robert Weissman wrote in the letter to hospital chief executives.

The move is part of a renewed effort to boost U.S. rates of breastfeeding, which is known to confer a wide range of health benefits from reducing obesity to boosting immunity and is recommended for at least a baby's first six months of life.

Just 14 percent of 6-month-old infants are exclusively breastfed, something U.S. health officials want to increase to about 26 percent by 2020. Breastfeeding also lags among lower-income women, according to the government data.

Still, breastfeeding in the United States is increasing, according to the World Health Organization, partly because more hospitals offer breastfeeding support and allow babies to stay in their mothers' hospital rooms.

About 66 percent of hospitals still give away formula, a 2009 Centers for Disease Control and Prevention report released last year found, down from nearly 73 percent in 2007.

Often the practice involves a corporate-sponsored tote bag from a formula company filled with samples of their product along with diapers, pamphlets and other items. Samples are often also mailed to people's homes along with coupons for more.

'MORE INFORMATION, NOT LESS'

The industry's trade group said such samples had been given away for more than 40 years and that most women wanted the bags.

"We can't forget that some moms even though they plan to breastfeed, they either can't or they decide not to," said International Formula Council Executive Vice President Mardi Mountford. "We believe they want more information, not less."

The consumer and health groups said in their letter that a hospital's involvement could sway women and that giving away formula samples worked against their other efforts. Rather than promoting breastfeeding, the packages of formula could encourage women to give up nursing their infants instead of seeking help and support, the groups said.

Once the free samples are gone, families also end up spending between $800 and $2,800 a year on formula, they added.

Some hospitals have already stopped formula giveaways, and a few states and cities have banned the practice.

The American Hospital Association, in a statement, said its members drafted policies based on mothers' preferences and that while breastfeeding was best, "having information and resources available for mothers who choose not to breastfeed is a responsible and supportive approach for the hospital."

Representatives for Abbott, Mead Johnson and Nestle did not immediately return requests for comment.